Transcriptome changes between compatible and incompatible graft combination of Litchi chinensis by digital gene expression profile

Abstract

Plant grafting has been practiced widely in horticulture and proved as a useful tool in science. However, the mechanisms of graft healing or graft incompatibility remain poorly understood. In this study, Litchi chinensis cv. ‘Jingganghongnuo’ homograft (‘J/J’) and ‘Jingganghongnuo’/‘zhuangyuanhong’ heterograft (‘J/Z’) as compatible and incompatible combination, respectively, was used to study transcriptional changes between incompatible and compatible graft during graft union formation. Anatomical observation indicated that three stages (2 h, 14 d and 21 d after grafting) were critical for graft union formation and selected for high-throughput sequencing. Results indicated 6060 DEGs were differentially expressed in the compatible combination and 5267 DEGs exhibiting in the incompatible one. KEGG pathway enrichment analysis revealed that DEGs were involved in metabolism, wound response, phenylpropanoid biosynthesis and plant hormone signal transduction. The expression of 9 DEGs annotated in auxin pathway was up-regulated in compatible combination than that in incompatible combination. The IAA concentration confirmed that the IAA might promote the graft compatibility. In addition, 13 DEGs related to lignin biosynthesis were differentially expressed during graft healing process. Overall, our results provide abundant sequence resources for studying mechanisms underlying graft compatibility and establish a platform for further studies of litchi and other evergreen fruit trees.

Plasma membrane H+‐ATPase activity and graft success of breadfruit (Artocarpus altilis) onto interspecific rootstocks of marang (A. odoratissimus) and pedalai (A. sericicarpus)

“…Members of the PM ATPase gene family were up‐regulated at the graft interface of litchi ( Litchi chinensis ) for compatible grafts at 14 and 21 day after grafting (Chen et al . ). The PM ATPase genes were also up‐regulated at the graft union of grapevine heterograft 14 day after grafting (Cookson et al .…”

Anin vitrografting method to quantify mechanical forces of adhering tissues

“…Using this system, we first showed that exogenous treatment with cellulases promotes graft adhesion. Given that numerous candidate genes related to grafting have been identified through recent transcriptome analyses (Cookson et al 2014;Liu et al 2015;Melnyk et al 2015;Li et al 2016;Chen et al 2017;Wang et al 2019;Xie et al 2019;Kurotani et al 2020;Notaguchi et al 2020 Figure 3C). In both cases, no correlation was observed between adhesive force and graft area.…”

“…In regard to molecular mechanisms, studies have revealed the activity of enzymes, such as peroxidase and catalase, during grafting (Fernández-garcía et al 2004;Pina and Errea 2008;Irisarri et al 2015). Molecular genetic studies of grafting have been conducted in fruit trees, vegetables, and model plants (Cookson et al 2014;Wang et al 2014;Liu et al 2015;Melnyk et al 2015;Irisarri et al 2015;Li et al 2016;Matsuoka et al 2016;Chen et al 2017;Melnyk et al 2016;Matsuoka et al 2018;Wang et al 2019;Xie et al 2019;Kurotani et al 2020;Notaguchi et al 2020). Among the various findings, these studies have clearly shown that grafting is promoted by auxin action through the expression of genes related to auxin signaling.…”

“…Among the various findings, these studies have clearly shown that grafting is promoted by auxin action through the expression of genes related to auxin signaling. The phytohormone auxin is transported basipetally from synthetic tissues, such as leaves and buds, by polar transport and accumulates at the damaged site (Yin et al 2012;Wang et al 2014;Liu et al 2015;Melnyk et al 2015;Matsuoka et al 2016;Chen et al 2017;Melnyk et al 2016;Kurotani et al 2020;Notaguchi et al 2020). Auxin promotes the formation of vascular strands when applied exogenously to undifferentiated tissue (Parkinson and Yeoman 1982;Wang et al 2014).…”

Autophagy is induced during plant grafting for wound healing

“…Not only phytohormone action, many of the genes related to metabolism, the oxidative stress response, transport, and defense are involved in graft healing process. Transcriptomic analyses conducted on the grafts of fruit trees (Chen et al , 2017; Assunção et al , 2019) and the seedling grafts of Arabidopsis (Melnyk et al , 2018) and tomato (Wang et al ., 2019; Xie et al , 2019) identified that graft incision induced drastic transcriptomic changes including upregulation of the wound response genes after grafting.…”